Contact tray for a mass transfer column

ABSTRACT

A contact tray for use in a mass transfer column and having a tray deck for receiving a liquid stream and a plurality of valves distributed across the tray deck through which vapor ascends for interacting with the liquid stream. Each valve has an opening in the tray deck in the form of a central segment and extensions that extend outwardly from opposite ends of the central segment. The valves each include a valve body with a valve cover positioned in covering relationship above and extending outwardly beyond the opening and legs that are attached to the valve cover at recesses located at opposite ends of the valve cover. The legs extend downwardly through the extensions in the opening and include stops in portions of the legs positioned below the tray deck to permit limited vertical movement of the legs to allow the valve body to move between open and closed positions in response to ascending vapor pressure against an undersurface of the valve cover. Deflectors are positioned at opposite sides of the legs to restrict vapor passage around the legs.

BACKGROUND OF THE INVENTION

The present invention relates generally to columns in which masstransfer and heat exchange occur and, more particularly, to contacttrays for use in such columns to facilitate interaction between fluidstreams flowing within the columns.

Mass transfer columns are configured to contact at least two fluidstreams in order to provide product streams of specific compositionand/or temperature. The term “mass transfer column,” as used herein isintended to encompass columns in which mass and/or heat transfer is theprimary objective. Some mass transfer columns, such as those utilized inmulticomponent distillation and absorption applications, contact agas-phase stream with a liquid-phase stream, while others, such asextraction columns, may be designed to facilitate contact between twoliquid phases of different densities. Oftentimes, mass transfer columnsare configured to contact an ascending vapor or liquid stream with adescending liquid stream, usually along or above the surfaces of masstransfer structures that are placed in the interior region of the columnto facilitate intimate contact between the two fluid phases. The rateand/or degree of mass and heat transferred between the two phases isenhanced by these mass transfer structures, which may be in the form ofvarious types of trays, structured packing, random packing, or gridpacking.

The trays used in mass transfer columns normally extend horizontallyacross substantially the entire horizontal cross section of the columnand are supported around their perimeter by rings welded to the innersurface of the circular column wall or shell. A number of trays arepositioned in vertically spaced-apart relationship. The trays may belocated in only a portion of the column to perform one part of amulti-step process occurring with the column. Alternatively, the traysmay fill substantially the entire open area within the column.

Trays of the type described above contain one or more downcomers thatare positioned at openings in the tray deck to provide passageways forliquid to descend from one tray to an adjacent lower tray. Prior toentering the downcomer, the liquid on the tray deck interacts withascending vapor that passes through openings provided in selectedportions of the tray deck. Those areas of the tray deck containing vaporopenings are commonly referred to as “active” areas because of the vaporand liquid mixing and frothing that occurs above those areas of thetray.

The vapor openings in the tray deck can be simple sieve holes or can beformed as part of fixed or moveable valves. Conventional valves havevalve covers supported over the opening in the tray deck by legs. Infixed valves, the valve cover is fixed against vertical movement. Inmoveable valves, the valve cover is able to move up and down in responseto variations in the pressure of vapor or fluid ascending through theopening. To allow vertical movement of the valve cover, the legs extendthrough the vapor openings or other openings in the tray deck andinclude a lower portion that is bent to contact an underside of the traydeck and thereby limit the range of vertical movement of the valvecover. The bending of the lower portions of the legs after they havebeen inserted through the vapor opening or other openings in the traydeck is labor-intensive and significantly increases the time required toassemble the valves in the trays.

In some valves, the lower portions of the legs are pre-bent in oppositedirections. By squeezing the lower portions of the legs toward eachother, the bent portions of the legs can be inserted through the vaporopening. When the pressure is released, the bent portions move away fromeach other and are able to engage against the underside of the tray deckto prevent removal of the legs from the vapor opening. While insertingthe legs into the vapor opening in this manner facilitates the assemblyof the valves in the tray, the legs extend outwardly beyond the valvecover and create unshielded regions where vapor can escape from thedesired flow direction when exiting the valve. A need has thus developedfor an improved valve that is readily assembled and restricts vapor fromescaping from the valve in undesired flow directions.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to a contact tray foruse in a mass transfer column. The contact tray comprises a tray deckfor receiving a liquid stream and a plurality of valves distributedacross the tray deck. Each of the valves comprises an opening in thetray deck to allow for passage of fluid through the tray deck forinteraction with the liquid stream when it is received on the tray deck.The opening has a central segment and extensions that extend outwardlyfrom opposite ends of the central segment. The valves each includes wallsegments that extend upwardly along opposite sides of the centralsegment of the opening and a valve body comprising a valve coverpositioned in covering relationship above the opening. The valve bodyincludes legs that are attached to the valve cover at recesses locatedat opposite ends of the valve cover and extend downwardly through theextensions in the opening. The valve cover has sides that extendoutwardly beyond the sides of the opening.

In other aspects, the central segment of the opening may be circular andthe extensions may be rectangular. The lower portion of each of the legsmay include at least one stop for contact against the tray deck to limitthe vertical movement of the legs within the extensions of the opening.Deflectors may be positioned adjacent opposite sides of the legs andextend downwardly below the sides of the valve cover to restrict vaporpassage around the legs. The sides of the valve cover may be curved.

In another aspect, the present invention is directed to the contact trayin which each of the valves comprises: an opening in the tray deck toallow for passage of vapor through the tray deck for interaction withthe liquid stream when it is received on the tray deck, the openinghaving a central segment and extensions that extend outwardly fromopposite ends of the central segment and include transversely-extendingslots, wall segments that extend upwardly along opposite sides of thecentral segment of the opening, and a valve body comprising atrapezoidal valve cover positioned in covering relationship above theopening and extensions and having legs that are attached to the valvecover at opposite ends of the valve cover and extend downwardly throughsaid slots in the extensions of the opening, wherein said valve coverhas sides that extend outwardly beyond the sides of the central segmentand the extensions of the opening.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompany drawings that form part of the specification and inwhich like reference numerals are used to indicate like components inthe various views:

FIG. 1 is a fragmentary, perspective view of a mass transfer column inwhich a portion of a shell of the column is broken away to show oneembodiment of contact trays of the present invention;

FIG. 2 is a perspective view of the contact trays in the column shown inFIG. 1, and shown on an enlarged scale from that used in FIG. 1;

FIG. 3 is a fragmentary, partially-exploded perspective view of one ofthe contact trays of FIGS. 1 and 2, showing valves of the contact trayon a further enlarged scale and with one row of the valves shown in aclosed position and the other row shown in an open position;

FIG. 4 is a fragmentary top plan view of a portion of the contact trayshown in FIG. 3 with a valve body of one of the valves removed;

FIG. 5 is a side elevation view of the contact tray taken in verticalsection along line 5-5 of FIG. 4 in the direction of the arrows andshown on a further enlarged scale with one of the valves in the closedposition and the other valve in the open position;

FIG. 6 is an elevation view of the contact tray and the closed valveshown in FIG. 5 and taken in vertical section along line 6-6 of FIG. 5in the direction of the arrows;

FIG. 7 is an elevation view of the contact tray and the open valve shownin FIG. 5 and taken in vertical section along line 7-7 of FIG. 5 in thedirection of the arrows;

FIG. 8 is a top perspective view of the contact tray and the open valveshown in FIG. 7;

FIG. 9 is a bottom perspective view of the contact tray and the openvalve;

FIG. 10 is a side elevation view of the contact tray and the open valve;

FIG. 11 is a top plan view of the contact tray and the open valve;

FIG. 12 is a downstream end elevation view of the contact tray and theopen valve;

FIG. 13 is an upstream end elevation view of the contact tray and theopen valve;

FIG. 14 is a bottom elevation view of the contact tray and the openvalve;

FIG. 15 is a top perspective view of one of the valve bodies shown fromthe downstream end of the valve body;

FIG. 16 is a bottom perspective view of the valve body shown in FIG. 15;

FIG. 17 is a top perspective view of the valve body shown from theupstream end of the valve cover;

FIG. 18 is a downstream end elevation view of the valve body;

FIG. 19 is a side elevation view of the valve body;

FIG. 20 is an upstream end elevation view of the valve body;

FIG. 21 is a top plan view of the valve body;

FIG. 22 is a bottom plan view of the valve body;

FIG. 23 is a fragmentary, partially-exploded perspective view of anotherone of the contact trays having a second valve embodiment;

FIG. 24 is a fragmentary top plan view of a portion of the contact trayshown in FIG. 23 with a valve body of one of the valves removed;

FIG. 25 is a side elevation view of the contact tray taken in verticalsection along line 25-25 of FIG. 24 in the direction of the arrows andshown on a further enlarged scale with one of the valves in the closedposition and the other valve in the open position;

FIG. 26 is an elevation view of the contact tray and the closed valveshown in FIG. 25 and taken in vertical section along line 26-26 of FIG.25 in the direction of the arrows;

FIG. 27 is an elevation view of the contact tray and the open valveshown in FIG. 25 and taken in vertical section along line 27-27 of FIG.25 in the direction of the arrows;

FIG. 28 is a top perspective view of the contact tray and the open valveshown in FIG. 27;

FIG. 29 is a bottom perspective view of the contact tray and the secondvalve embodiment in an open position;

FIG. 30 is a side elevation view of the contact tray and the open valve;

FIG. 31 is a top plan view of the contact tray and the open valve;

FIG. 32 is a downstream end elevation view of the contact tray and theopen valve;

FIG. 33 is an upstream end elevation view of the contact tray and theopen valve;

FIG. 34 is a bottom elevation view of the contact tray and the openvalve;

FIG. 35 is a top perspective view of one of the valve bodies shown fromthe downstream end of the valve body;

FIG. 36 is a bottom perspective view of the valve body shown in FIG. 35;

FIG. 37 is a top perspective view of the valve body shown from theupstream end of the valve body;

FIG. 38 is a downstream end elevation view of the valve body;

FIG. 39 is a side elevation view of the valve body;

FIG. 40 is an upstream end elevation view of the valve body;

FIG. 41 is a top plan view of the valve body;

FIG. 42 is a bottom plan view of the valve body;

FIG. 43 is a fragmentary, partially-exploded perspective view of afurther one of the contact trays having a third valve embodiment;

FIG. 44 is a fragmentary top plan view of a portion of the contact trayshown in FIG. 43 with a valve body of one of the valves removed;

FIG. 45 is a side elevation view of the contact tray taken in verticalsection along line 45-45 of FIG. 44 in the direction of the arrows andshown on a further enlarged scale with one of the valves in the closedposition and the other valve in the open position;

FIG. 46 is an elevation view of the contact tray and the closed valveshown in FIG. 45 and taken in vertical section along line 46-46 of FIG.45 in the direction of the arrows;

FIG. 47 is an elevation view of the contact tray and the open valveshown in FIG. 45 and taken in vertical section along line 47-47 of FIG.45 in the direction of the arrows;

FIG. 48 is a top perspective view of the contact tray and the open valveshown in FIG. 47;

FIG. 49 is a bottom perspective view of the contact tray and the thirdvalve embodiment in an open position;

FIG. 50 is a side elevation view of the contact tray and the open valve;

FIG. 51 is a top plan view of the contact tray and the open valve;

FIG. 52 is a downstream end elevation view of the contact tray and theopen valve;

FIG. 53 is an upstream end elevation view of the contact tray and theopen valve;

FIG. 54 is a bottom elevation view of the contact tray and the openvalve;

FIG. 55 is a fragmentary, partially-exploded perspective view of afurther one of the contact trays having a fourth valve embodiment;

FIG. 56 is a fragmentary top plan view of a portion of the contact trayshown in FIG. 55 with a valve body of one of the valves removed;

FIG. 57 is a side elevation view of the contact tray taken in verticalsection along line 57-57 of FIG. 56 in the direction of the arrows andshown on a further enlarged scale with one of the valves in the closedposition and the other valve in the open position;

FIG. 58 is an elevation view of the contact tray and the closed valveshown in FIG. 57 and taken in vertical section along line 58-58 of FIG.57 in the direction of the arrows;

FIG. 59 is an elevation view of the contact tray and the open valveshown in FIG. 57 and taken in vertical section along line 59-59 of FIG.57 in the direction of the arrows;

FIG. 60 is a top perspective view of the contact tray and the open valveshown in FIG. 59;

FIG. 61 is a bottom perspective view of the contact tray and the fourthvalve embodiment in an open position;

FIG. 62 is a side elevation view of the contact tray and the open valve;

FIG. 63 is a top plan view of the contact tray and the open valve;

FIG. 64 is a downstream end elevation view of the contact tray and theopen valve;

FIG. 65 is an upstream end elevation view of the contact tray and theopen valve;

FIG. 66 is a bottom elevation view of the contact tray and the openvalve;

FIG. 67 is a top perspective view of one of the valve bodies from thethird and fourth valve embodiments shown from the downstream end of thevalve body;

FIG. 68 is a bottom perspective view of the valve body shown in FIG. 67;

FIG. 69 is a top perspective view of the valve body shown from theupstream end of the valve body;

FIG. 70 is a downstream end elevation view of the valve body;

FIG. 71 is a side elevation view of the valve body;

FIG. 72 is an upstream end elevation view of the valve body;

FIG. 73 is a top plan view of the valve body;

FIG. 74 is a bottom plan view of the valve body;

FIG. 75 is a fragmentary, partially-exploded perspective view of afurther one of the contact trays having a fifth valve embodiment;

FIG. 76 is a fragmentary top plan view of a portion of the contact trayshown in FIG. 75 with a valve body of one of the valves removed;

FIG. 77 is a side elevation view of the contact tray taken in verticalsection along line 77-77 of FIG. 76 in the direction of the arrows andshown on a further enlarged scale with one of the valves in the closedposition and the other valve in the open position;

FIG. 78 is an elevation view of the contact tray and the closed valveshown in FIG. 77 and taken in vertical section along line 78-78 of FIG.77 in the direction of the arrows;

FIG. 79 is an elevation view of the contact tray and the open valveshown in FIG. 77 and taken in vertical section along line 79-79 of FIG.77 in the direction of the arrows;

FIG. 80 is a top perspective view of the contact tray and the open valveshown in FIG. 79;

FIG. 81 is a bottom perspective view of the contact tray and the fifthvalve embodiment in an open position;

FIG. 82 is a side elevation view of the contact tray and the open valve;

FIG. 83 is a top plan view of the contact tray and the open valve;

FIG. 84 is a downstream end elevation view of the contact tray and theopen valve;

FIG. 85 is an upstream end elevation view of the contact tray and theopen valve;

FIG. 86 is a bottom elevation view of the contact tray and the openvalve;

FIG. 87 is a top perspective view of one of the valve bodies from thefifth valve embodiment shown from the downstream end of the valve body;

FIG. 88 is a bottom perspective view of the valve body shown in FIG. 87;

FIG. 89 is a top perspective view of the valve body shown from theupstream end of the valve body;

FIG. 90 is a downstream end elevation view of the valve body;

FIG. 91 is a side elevation view of the valve body;

FIG. 92 is an upstream end elevation view of the valve body;

FIG. 93 is a top plan view of the valve body; and

FIG. 94 is a bottom plan view of the valve body.

DETAILED DESCRIPTION

Turning now to the drawings in greater detail and initially to FIG. 1, amass transfer column suitable for use in mass transfer or heat exchangeprocesses is represented generally by the numeral 10. The mass transfercolumn 10 includes an upright, external shell 12 that may be cylindricalin configuration, although other configurations, including polygonal,are possible and are within the scope of the present invention. Theshell 12 may be of any suitable diameter and height and may beconstructed from one or more rigid materials that are desirably inertto, or are otherwise compatible with, the fluids and conditions presentduring operation of the mass transfer column 10.

The mass transfer column 10 may be of a type used for processing fluidstreams, typically liquid or vapor streams, to obtain fractionationproducts or to otherwise cause mass transfer or heat exchange betweenthe fluid streams. For example, the mass transfer column 10 may be onein which crude atmospheric, lube vacuum, crude vacuum, fluid or thermalcracking fractionating, coker or visbreaker fractionating, cokescrubbing, reactor off-gas scrubbing, gas quenching, edible oildeodorization, pollution control scrubbing, or other processes occur.

The shell 12 of the mass transfer column 10 defines an open internalregion 14 in which the desired mass transfer or heat exchange betweenthe fluid streams occurs. In one implementation, the fluid streams maycomprise one or more ascending vapor streams and one or more descendingliquid streams. In other implementations, the fluid streams may comprisesubstantially any combination of ascending or descending liquid streamsor ascending or descending vapor streams.

One or more fluid streams may be directed into the mass transfer column10 through any number of feed lines, such as lower feed line 16 andupper feed line 18, positioned at appropriate locations along the heightof the mass transfer column 10. In one implementation, vapor streams maybe generated within the mass transfer column 10 rather than beingintroduced into the mass transfer column 10 through the feed lines 16and 18. One or more fluid streams may be directed out of the masstransfer column 10 through any number of takeoff lines, such as lowertakeoff line 20 and upper takeoff line 22. In one implementation, liquidmay be introduced through upper feed line 18, descend through the masstransfer column 10, and be removed through lower takeoff line 20, whilevapor may be introduced through lower feed line 16, ascend through themass transfer column 10, and be removed through upper takeoff line 22.

Other mass transfer column components that would typically be present,such as reflux stream lines, reboilers, condensers, vapor horns, liquiddistributors, and the like, are not illustrated in the figures becausethey are conventional in nature and an illustration of these componentsis not believed to be necessary for an understanding of the presentinvention.

A plurality of contact trays 24 are positioned within the open internalregion 14 of the mass transfer column 10 to facilitate interaction ofthe fluids flowing within the open internal region 14. The contact trays24 extend generally horizontally across the entire cross-section of themass transfer column 10 and are arranged in vertically spaced-apartrelationship to each other. The specific design of each contact tray 24can be varied while remaining within the scope of the present invention.

In the illustrated embodiment of FIGS. 1-2, the contact trays 24 areconstructed to form a single-pass fluid flow arrangement in which aliquid stream flows end-to-end in one direction on one of the contacttrays 24 and then descends to a lower adjacent one of the contact trays24 where it flows end-to-end in the opposite flow direction. Each of thecontact trays 24 has a side downcomer 26 that is positioned at one endof a tray deck 28 that may be formed from interconnected individual traypanels. The side downcomer 26 receives and removes the descending liquidstream from the tray deck 28 of the associated contact tray 24 anddelivers it to one end of the tray deck 28 of an underlying one of thecontact trays 24. The liquid stream received on that tray deck 28 thenflows across the tray deck 28 in an opposite direction to the sidedowncomer 26 that is positioned at the opposite end of the tray deck 28.The liquid stream enters the side downcomer 26 and is delivered to thetray deck 28 of the next underlying contact tray 24. This flow patternis repeated on each successive one of the of the contact trays 24.Although the trays 24 are illustrated as being constructed forsingle-pass fluid flow, the invention encompasses trays constructed formulti-pass flow.

A plurality of valves 30 is distributed across the tray decks 28 of thecontact trays 24 to allow vapor or another fluid to ascend through thetray decks 28 and interact with the liquid flowing across the uppersurface of the tray decks 28. The area of the tray decks 28 containingthese valves 30 is normally referred to as the active area of thecontact trays 24. The valves 30 are positioned in a preselectedarrangement on the active area. The valves 30 are shown as beingarranged in parallel rows with the valves 30 adjacent rows staggered toform a triangular pitch. In an example of another arrangement, thevalves 30 in adjacent rows are aligned to form a square pitch.

The area of the tray deck 28 on each contact tray 24 that underlies theside downcomer 26 of the overlying one of the contact trays 24 comprisesan inlet panel 32. The inlet panel 32 is normally imperforate or hasshielded flow passages that impede or prevent the descending fluid frompassing through the inlet panel 32.

The side downcomer 26 of each contact tray 24 comprises a downcomer wall34 that extends in a chordal fashion across the open internal region 14of the mass transfer column 10 from opposite sides of the shell 12. Theupper portion of the downcomer wall 38, or a separate panel attached tothe downcomer wall 38, extends upwardly above the tray deck 26 to forman outlet weir 36 that causes liquid to accumulate on the tray deck 28before spilling over the outlet weir 36 and entering the side downcomer26, which delivers the liquid to the underlying tray deck 28. A lowerportion of the downcomer wall 34 is spaced above the underlying traydeck 28 or contains flow openings (not shown) to allow fluid to exit theside downcomer 26 and flow along the upper surface of the tray deck 28before entering the side downcomer 26 at the opposite end of the traydeck 28. The downcomer walls 34 are illustrated as being planar andvertically-extending, but stepped, sloped or multi-chordal walls orother constructions are within the scope of the invention.

Turning now to FIGS. 3-22, each of a first embodiment of the valves 30on the tray deck 28 comprises an opening 38 that extends through thetray deck 28 to allow for passage of fluid through the tray deck 28 forinteraction with the liquid stream when it is received on the tray deck28. As best seen in FIG. 4, the opening 38 has a central segment 40 aswell as two extensions 42 and 44 that extend outwardly from oppositeends of the central segment 40. In one embodiment, the central segment40 is round and the extensions 42 and 44 are rectangular. The extensions42 and 44 may each have a greatest width that is less than that of thecentral segment 40. The extensions 42 and 44 are aligned in the desiredflow direction of the liquid stream on the tray deck 28. The extension42 positioned in the upstream direction may have a greater width thanthat of the extension 44 positioned in the downstream direction. Othershapes for the central segment 40 and extensions 42 and 44 may be used.

The valves 30 may include wall segments 46 and 48 that extend upwardlyalong opposite sides of the central segment 40 of the opening 38. Thewall segments 46 and 48 may be formed by bending parts of the tray deck28 upwardly during a punching or other operation that is used to formthe openings 38. The wall segments 46 and 48 are curved and follow thecircular perimeter of the sides of the central segment 40 between theextensions 42 and 44.

Each valve 30 also includes a valve body 50 that comprises a valve cover52 and legs 54 and 56. The valve cover 52 has sides that extendoutwardly beyond the sides of the opening 38 in the tray deck 28 to moreeffectively shield the opening 38 against the detrimental downwardweeping of fluid through the opening 38. In one embodiment, the sides ofthe valve cover 52 extend downwardly to guide the flow of vaporascending through the opening 38 in a lateral direction to facilitateinteraction with the liquid stream on the tray deck 28. The sides of thevalve cover 52 may be curved or angled downwardly to achieve thisguiding function.

The legs 54 and 56 position the valve cover 52 in covering relationshipabove the opening 38 in the tray deck 28. Two legs 54 and 56 are used inthe illustrated embodiment to position the valve cover 52, butadditional legs could be used if desired. The legs 54 and 56 are locatedat opposite ends of the valve cover 50 and extend vertically. The valves30 are oriented on the tray deck 28 so that the legs 54 and 56 arealigned in the general direction of the desired flow of the liquidstream along the upper surface of the tray deck 28.

The legs 54 and 56 are attached at their upper ends to the valve cover52 at recesses 58 and 60 that are located at opposite ends of the valvecover 52. The legs 54 and 56 extend downwardly through the extensions 42and 44 of the opening 38. The legs 54 and 56 and the extensions 42 and44 are constructed so that the legs 54 and 56 are closely received andvertically moveable within the extensions 42 and 44 to allow the valvecover 52 to move up and down. The valve cover 52 moves verticallybetween an open position spaced above the opening 38 and, if present,the wall segments 46 and 48 and a closed position resting on or near thetray deck 28 or, if present, the wall segments 46 and 48.

The legs 54 and 56 in one embodiment have a greatest width that is lessthan that of the valve cover 52. One of the legs 54 or 56 may have awidth that is greater than the other one of the legs 54 or 56. Forexample, the upstream leg 54 may be wider than the downstream leg 56 tofacilitate the flow of the liquid stream around the valve 30 and impedeentry of liquid into the opening 38.

Each of the legs 54 and 56 has a lower portion that extends below thetray deck 28 and includes at least one stop 62 for contact against anunderside of the tray deck 28 to limit the vertical movement of the legs54 and 56 within the extensions 42 and 44 of the opening 38. In theillustrated embodiment, each of the legs 54 and 56 includes a pair ofthe stops 62 that are positioned in laterally spaced-apart relationshipto each other. The pairs of stops 62 in the legs 54 and 56 have upperends that are in a common plane that is parallel with the valve cover52. The lateral spacing and coplanar relationship of the pairs of stops62 is advantageous in that it helps to maintain the valve body 50 in thecorrect alignment with the valve cover 52 in a horizontal orientationwhen the pairs of stops 62 engage against the underside of the tray deck28. The valve body 50 is thus less likely to become misaligned and stickwhen it descends in a downward direction in response to a decrease invapor pressure during fluid processing within the mass transfer column10.

In one embodiment, the stops 62 are in the form of tabs that are bentoutwardly from the plane of the legs 54 and 56. The stops 62 areconstructed to prevent removal of the legs 54 and 56 from within theextensions 42 and 44 of the opening 38 during the operation of the masstransfer column and to allow the legs 54 and 56 to be inserted into theextensions 42 and 44 during assembly of the valves 30 by exerting aforce on the lower portions of the legs 54 and 56 to move them towardeach other a sufficient distance to allow the stops 62 to pass throughthe extensions 42 and 44. Upon release of the force, the legs 54 and 56move back to their original position extending in parallel relationshipto each other to seat the valve body 50 within the opening 38.

The valves 30 further include deflectors 64 and 66 that are positionedadjacent opposite sides of each one of the legs 54 and 56. Thedeflectors 64 and 66 are positioned outwardly of the legs 54 and 56 sothat they extend outwardly beyond and laterally of the extensions 42 and44 of the underlying opening 38 in the tray deck 28. The deflectors 64and 66 also extend downwardly below the sides of the valve cover 52 torestrict vapor passage around the legs 54 and 56 as it ascends throughthe opening 38 in the tray deck 28. In one embodiment, the deflectors 64and 66 are formed as downward extensions of the valve cover 52 and arepositioned at the ends of the valve cover 52 adjacent the recesses wherethe legs 54 and 56 are joined to the valve cover 52. The deflectors 64and 66 may extend downwardly a sufficient distance to engage against anupper surface of the tray deck 28 when the valve 30 is in the closedposition.

A second embodiment of the valves is shown in FIGS. 23-42 and isdesignated by the number 130. Valves 130 are similar to the valves 30shown in FIGS. 1-22 and like reference numerals with the prefix “1” havebeen used to designate the parts of the valves 130 that are similar tothe corresponding parts in the valves 30 of the first embodiment. Themain difference between valves 130 and valves 30 is only a single stop162 is used in the legs 154 and 156 of the valves 130 and it iscentrally positioned between the sides of the legs 154 or 156.

A third embodiment of the valves is shown in FIGS. 43-54 and isdesignated by the number 230. The valves 230 are positioned on a traydeck 228 and each valve 230 comprises an opening 238 that extendsthrough the tray deck 228 to allow for passage of fluid through the traydeck 228 for interaction with the liquid stream when it is received onthe tray deck 228. As best seen in FIG. 43, the opening 238 has acentral segment 240 as well as two extensions 242 and 244 that extendoutwardly from opposite ends of the central segment 240 and terminate intransversely-extending slots 245 a and 245 b. In one embodiment, thecentral segment 240 is round and the extensions 242 and 244 have arectangular segment leading to the narrow transverse slots 245 a and 245b. The rectangular segments of the extensions 242 and 244 may each havea greatest width that is less than that of the central segment 240 andthe slots 245 a and 245 b may each have a width that is greater thanthat of the central segment 240. The extensions 242 and 244 are alignedin the desired flow direction of the liquid stream on the tray deck 228.The extension 242 and its slot 245 a that are positioned in the upstreamdirection may have a greater width than that of the extension 244 andits slot 245 b that are positioned in the downstream direction. Othershapes for the central segment 240 and the extensions 242 and 244 may beused.

The valves 230 may include wall segments 246 and 248 that extendupwardly along opposite sides of the central segment 240 of the opening238 and the rectangular segments of the extensions 242 and 244. The wallsegments 246 and 248 may be formed by bending parts of the tray deck 228upwardly during a punching or other operation that is used to form theopenings 38. The wall segments 246 and 248 are curved as the follow thecircular perimeter of the sides of the central segment 240 and aregeneral linear as they follow along the sides of the rectangular segmentof the extensions 242 and 244.

Each valve 230 also includes a valve body 250 that comprises a valvecover 252 and legs 254 and 256. The valve cover 252 is generally planarand may have a polygonal configuration, such as the illustratedtrapezoidal configuration. The valve cover 252 is sized so that itssides and ends extend outwardly beyond the sides and ends of the centralsegment 240 and the extensions 242 and 244 of the opening 238 in thetray deck 228 to more effectively shield the opening 238 against thedetrimental downward weeping of fluid through the opening 238. In oneembodiment, the sides and ends of the valve cover 252 extend downwardlywith the sides guiding the flow of vapor ascending through the opening238 in a lateral direction to the overall direction of flow of theliquid stream on the tray deck 228 to facilitate interaction with theliquid stream on the tray deck 228. The sides of the valve cover 252 maybe curved or angled downwardly to achieve this guiding function.

The legs 254 and 256 position the valve cover 252 in coveringrelationship above the opening 238 and the extensions 242 and 244 in thetray deck 228. Two legs 254 and 256 are used in the illustratedembodiment to position the valve cover 252, but additional legs could beused if desired. The legs 254 and 256 are located at opposite ends ofthe valve cover 250 and extend vertically. The valves 230 are orientedon the tray deck 228 so that the legs 54 and 56 are aligned in thegeneral direction of the desired overall flow of the liquid stream alongthe upper surface of the tray deck 228.

The legs 254 and 256 are attached at their upper ends to the valve cover252 to the opposite ends of the valve cover 252. The legs 254 and 256extend downwardly through the slots 245 a and 245 b that communicatewith the extensions 42 and 44 and the opening 38. The legs 254 and 256and the slots 245 a and 245 b are constructed so that the legs 254 and256 are closely received and vertically moveable within the slots 245 aand 245 b to allow the valve cover 252 to move up and down. The valvecover 252 moves vertically between an open position spaced above theopening 238 and, if present, the wall segments 246 and 248 and a closedposition resting on or near the tray deck 228 or, if present, the wallsegments 246 and 248.

The legs 254 and 256 in one embodiment have a greatest widthcorresponding to the width of the corresponding end of the valve cover252. One of the legs 254 or 256 may have a width that is greater thanthe other one of the legs 254 or 256. For example, the upstream leg 254may be wider than the downstream leg 256 to facilitate the flow of theliquid stream around the valve 230 and impede entry of liquid into theopening 238.

Each of the legs 254 and 256 has a lower portion that extends below thetray deck 228 and includes at least one stop 262 for contact against anunderside of the tray deck 228 to limit the vertical movement of thelegs 254 and 256 within the slots 245 a and 245 b in the extensions 242and 244 of the opening 238. In the illustrated embodiment, each of thelegs 254 and 256 includes a pair of the stops 262 that are positioned inlaterally spaced-apart relationship to each other. The pairs of stops262 in the legs 254 and 256 have upper ends that are in a common planethat is parallel with the valve cover 252. The lateral spacing andcoplanar relationship of the pairs of stops 262 is advantageous in thatit helps to maintain the valve body 250 in the correct alignment withthe valve cover 252 in a horizontal orientation when the pairs of stops262 engage against the underside of the tray deck 228. The valve body250 is thus less likely to become misaligned and stick when it descendsin a downward direction in response to a decrease in vapor pressureduring fluid processing within the mass transfer column 10.

In one embodiment, the stops 262 are in the form of tabs that are bentoutwardly from the plane of the legs 254 and 256. The stops 262 areconstructed to prevent removal of the legs 254 and 256 from within theextensions 242 and 244 of the opening 238 during the operation of themass transfer column 10. During assembly of the valves 230, the legs 254and 256 may be inserted into the slots 245 a and 245 b before the stops262 are formed by bending of the tabs.

The stops 262 set the upper limit of the vertical movement of the valvebody 250 in response to vapor pressure against an underside of the valvecover 252. The lower limit of the vertical movement of the valve body250 may be set by the contact of the underside of the valve cover 252 onthe top of the wall segments 246 and 248, if present, or by the contactof shoulders 263 formed on the legs 254 and 256 against an upper surfaceof the tray deck 228.

The downstream leg 256 in each valve body 250 may include one or morevents 266 positioned to allow a portion of the vapor that ascendsthrough the opening 238 in the tray deck 228 to pass through thedownstream leg 256 and facilitate the directional flow of the liquidstream and vapor mixture or froth in the downstream direction. Anoverlying deflector 268 may be associated with the vent 266 to directthe vapor passing through the vent 266 in a downward direction towardthe tray deck 228 to enhance the mixing of the vapor with the liquidstream.

A fourth embodiment of the valves is designated by the number 330 inFIGS. 55-74, in which like reference numbers with the prefix “3” havebeen used to designate parts of the valves 330 that are the same orsimilar to the corresponding parts of the valves 230. Valves 330 are thesame as the valves 230 shown in FIGS. 23-42 except the opening 338 doesnot include the extensions 242 and 244 that are used with the opening238. Instead, the slots 345 a and 345 b in the tray deck 328 throughwhich the legs 354 and 356 extend are not connected to the opening 238and a single wall 346 surrounds the opening.

A fifth embodiment of the valves is designated by the number 430 inFIGS. 75-94, in which like reference numbers with the prefix “4” areused to designate parts of the valves that are the same or similar tothe corresponding parts of the valves 230. Valves 430 are the same asvalves 230, except that only a single stop 162 is used in the legs 454and 456 of the valves 430 and it is centrally positioned between thesides of the legs 454 or 456.

From the foregoing, it will be seen that this invention is one welladapted to attain all the ends and objectives hereinabove set forthtogether with other advantages that are inherent to the structure.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theinvention.

Since many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

1-21. (canceled)
 22. A contact tray for use in a mass transfer column,said contact tray comprising: a tray deck for receiving a liquid stream;and a plurality of valves distributed across the tray deck, each of saidvalves comprising: an opening in the tray deck to allow for passage ofvapor through the tray deck for interaction with the liquid stream whenit is received on the tray deck, said opening having a central segmentand extensions that extend outwardly from opposite ends of the centralsegment and include transversely-extending slots; wall segments thatextend upwardly along opposite sides of the central segment of theopening; and a valve body comprising a trapezoidal valve coverpositioned in covering relationship above said opening and extensionsand having legs that are attached to the valve cover at opposite ends ofthe valve cover and extend downwardly through said slots in theextensions of the opening, wherein said valve cover has sides thatextend outwardly beyond the sides of the central segment and theextensions of the opening.
 23. The contract tray as set forth in claim22, wherein each of said legs has a lower portion that extends belowsaid tray deck and includes a stop for contact against said tray deck tolimit said vertical movement of the legs within said slots in theextensions of the opening.
 24. The contact tray as set forth in claim23, wherein the lower portion of at least one of said legs includes apair of said stops positioned in laterally spaced-apart relationship toeach other.
 25. The contact tray as set forth in claim 23, wherein thesides of the valve cover extend downwardly.
 26. The contact tray as setforth in claim 25, including a vent positioned in one of said legs toallow passage of vapor through said one leg after the vapor passesthrough the opening.
 27. A contact tray for use in a mass transfercolumn, said contact tray comprising: a tray deck for receiving a liquidstream; and a plurality of valves distributed across the tray deck, eachof said valves comprising: an opening in the tray deck to allow forpassage of vapor through the tray deck for interaction with the liquidstream when it is received on the tray deck, said opening having acentral segment and extensions that extend outwardly from opposite endsof the central segment and include transversely-extending slots; wallsegments that extend upwardly along opposite sides of the centralsegment of the opening; and a valve body comprising: a trapezoidal valvecover positioned in covering relationship above said opening andextensions, said valve cover having sides that extend outwardly beyondthe sides of the central segment and the extensions of the opening; legsthat are attached to the valve cover at opposite ends of the valve coverand extend downwardly through said slots in the extensions of theopening, each of said legs having a lower portion that extends belowsaid tray deck and includes a stop for contact against said tray deck tolimit said vertical movement of the legs within said slots in theextensions of the opening; and a vent positioned in one of said legs toallow passage of vapor through said one leg after the vapor passesthrough the opening.
 28. The contact tray as set forth in claim 27,wherein the sides of the valve cover extend downwardly.
 29. The contacttray as set forth in claim 27, wherein the lower portion of at least oneof said legs includes a pair of said stops positioned in laterallyspaced-apart relationship to each other.
 30. The contact tray as setforth in claim 29, including a vent positioned in one of said legs toallow passage of vapor through said one leg after the vapor passesthrough the opening.
 31. A contact tray for use in a mass transfercolumn, said contact tray comprising: a tray deck for receiving a liquidstream; and a plurality of valves distributed across the tray deck, eachof said valves comprising: an opening in the tray deck to allow forpassage of vapor through the tray deck for interaction with the liquidstream when it is received on the tray deck, said opening having acentral segment and extensions that extend outwardly from opposite endsof the central segment and include transversely-extending slots; wallsegments that extend upwardly along opposite sides of the centralsegment of the opening; and a valve body comprising: a trapezoidal valvecover positioned in covering relationship above said opening andextensions, said valve cover having sides that extend downwardly andoutwardly beyond the sides of the central segment and the extensions ofthe opening; legs that are attached to the valve cover at opposite endsof the valve cover and extend downwardly through said slots in theextensions of the opening; and a vent positioned in one of said legs toallow passage of vapor through said one leg after the vapor passesthrough the opening.
 32. The contact tray as set forth in claim 31,wherein each of said legs has a lower portion that extends below saidtray deck and includes a stop for contact against said tray deck tolimit said vertical movement of the legs within said slots in theextensions of the opening.
 33. The contact tray as set forth in claim32, wherein the lower portion of at least one of said legs includes apair of said stops positioned in laterally spaced-apart relationship toeach other